DISCLAIMER: The cases / examples on this blog have been anonymised to maintain confidentiality of patients. Cases have been acquired from various international hospitals and through other medical colleagues with the intention to teach through case examples.

Sunday, 11 October 2009

This patient with inoperable gastric carcinoma was commenced on palliative chemotherapy several months before the current admission. However, there was development of intermittent fever several days after the insertion of a tunneled Hickman line. The patient was not found to be neutropaenic.

Blood cultures were taken from the peripheral veins and from the line - both grew coagulase negative staphylococci (CNS). The CNS were sensitive to minocycline and flucloxacillin (anti-staph penicillin).

The patient did not want to remain hospitalised. As the patient was otherwise well, long term oral minocycline therapy was commenced to try and eradicate the infection as an outpatient.

The patient was readmitted after several weeks with continuing fevers and rigors. There was no redness or pus around the entry site of the tunneled line. Again, cultures were positive for the same coagulase negative staphylococci from the line and peripheral veins.

Below is the nail change found in the this patient, which was symmetrical in both hands.

This blueish discolouration of the proximal nail is a rare but typical finding of long term minocycline therapy.

Please note that tetracycline antibiotics are chelators (e.g. bind iron, magnesium and calcium) and should be avoided in pregnancy (foetal harm), breast feeding women and children less than 12 years old (tooth discoloration and bone hypoplasia; BNF 57). Tetracyclines can exacerbate renal failure and should be avoided. If long term administration is desired (e.g. acne), hepatoxicity and pigmentation should be checked for every 3 months (BNF 57). If these side effects or SLE develops (very rare complication), the drug should be discontinued.

This patient was eventually treated with intravenous flucloxacillin, given via the Hickman line with resolution of the infection after 10-days of therapy. Transthoracicechocardiogram revealed no evidence of valvular vegetation.

Remember that common things are common - when you get fever and rigors in a patient with long term venous line, think of line infection as a differential diagnosis in your assessment.

However, oral antibiotic therapy is not the standard to treat such an infection. The current approach is to use IV antibiotics given via the line to try and eradicate the infection. Other methods include 'antibiotic lock' therapy by instilling antibiotic into the line under a 'hub lock' to keep the antibiotic within the line to kill the infection. More evidence is required to determine its efficacy.

Central venous catheter infections can be difficult to successfully treat by IV antibiotics even given by the line and as a consequence, there should be a low-threshold for removing it. Some advocate exchanging the old line for a new one over a guidewire but there is the obvious concern of transferring such infection onto the guidewire and then on to the new line. Moreover, there are risks of further bacteraemia and dissemination of septic emboli and such practise is generally discouraged especially when there is obvious soft tissue infection around and deep to the line.

Learning Point: Blue discolouration of the nails is not normal. Please do a chart biopsy and find out which drugs the patient has been taking.